Metallic taste in mouth

For more than 5 days, I've had this taste in my mouth. A metallic taste that causes nausea. I can't figure out what's the cause. My GERD sometimes brings this about but not for that long. I took all possible stomach meds and Gaviscon Advance but in vain.
Could my ear problem be the culprit? Last Tuesday, I saw an ENT coz of sudden hear loss. He performed cleaning of the ear and discovered I had a severe infection and an ear polyp. So, he cauterized the ear polyp w silver nitrate and put a medicine in both ears to treat the infection. The procedure was very painful as he didn't give me any kind of anesthetic. When I asked what I should do next, he said nothing. My ear is still itchy and hurts. Could this be the cause of the metallic taste or is it GERD and gastritis?

No, I don't take any antibiotics. Yes, it's exactly like the metallic taste flagyl causes.

I used to 2 months ago but not any more.

Yes, it's quite weird that they might trigger nausea after all these years. Still, it could be. With our disease nothing is impossible.